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@ARTICLE{Rost:1005325,
author = {Rost, Stefan and Blügel, Stefan and Friedrich, Christoph},
title = {{E}fficient calculation of k -integrated electron energy
loss spectra: {A}pplication to monolayers of {M}o{S} 2 ,
h{BN} , and graphene},
journal = {Physical review / B},
volume = {107},
number = {8},
issn = {2469-9950},
address = {Woodbury, NY},
publisher = {Inst.},
reportid = {FZJ-2023-01434},
pages = {085132},
year = {2023},
abstract = {The theoretical scattering cross section of electron energy
loss spectroscopy (EELS) is essentially given by
$-\text{Im}\,\varepsilon^{-1}(\mathbf{k},\omega)$ with the
energy loss $\hbar\omega$ and the momentum transfer
$\hbar\mathbf{k}$. The macroscopic dielectric function
$\varepsilon(\mathbf{k},\omega)$ can be calculated from
first principles using time-dependent density-functional
theory.However, experimental EELS measurements have a finite
$\mathbf{k}$ resolution or, when operated in spatial
resolution mode, yield a $\mathbf{k}$-integrated loss
spectrum, which deviates significantly from EEL spectra
calculated for specific $\mathbf{k}$ momenta. On the other
hand, integrating the theoretical spectra over $\mathbf{k}$
is complicated by the fact that the integrand varies over
several (typically six) orders of magnitude around $k=0$.In
this article, we present a stable technique for integrating
EEL spectra over an adjustable range of momentum transfers.
The important region around $k=0$, where the integrand is
nearly divergent, is treated partially analytically,
allowing an analytic integration of the near-divergence. The
scheme is applied to three prototypical two-dimensional
systems: monolayers of MoS$_2$ (semiconductor), hexagonal BN
(insulator), and graphene (semimetal).Here, we are
confronted with the added difficulty that the long-range
Coulomb interaction leads to a very slow supercell (vacuum
size) convergence. We address this difficulty by employing
an extrapolation scheme, enabling an efficient reduction of
the supercell size and thus a considerable speed-up in
computation time. The calculated $\mathbf{k}$-integrated
spectra are in very favourable agreement with experimental
EEL spectra.},
cin = {PGI-1},
ddc = {530},
cid = {I:(DE-Juel1)PGI-1-20110106},
pnm = {5211 - Topological Matter (POF4-521)},
pid = {G:(DE-HGF)POF4-5211},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000944014500003},
doi = {10.1103/PhysRevB.107.085132},
url = {https://juser.fz-juelich.de/record/1005325},
}